Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

533
FXUS63 KLOT 071130
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
630 AM CDT Tue Apr 7 2026

.KEY MESSAGES...

- Brief chance (~30 percent) for a light wintry mix mainly north
  of I-88 tonight.

- Breezy/windy and warmer Wednesday.

- Mild with periods of showers and some storms Wednesday night
  into at least Friday, and again from later in the weekend into
  early next week.

&&

.DISCUSSION...
Issued at 257 AM CDT Tue Apr 7 2026

Early morning surface analysis places 1034 mb high pressure
across the upper Mississippi Valley. Breezy north-northeast low-
level flow downstream of the center of the high was pulling
colder air into the forecast area, with current temperatures
generally in the low-mid 30s. The combination of somewhat breezy
winds and patchy cloud cover (especially just inland of Lake
Michigan across the Chicago metro area) has helped keep temps up
a little from previous forecast, though no doubt we`ll see some
mid-upper 20s across far northern IL over the next few hours
especially north of I-88 or so. This colder air mass is also
quite dry, as noted by surface dew points in the teens (and even
some single digits), which has limited the depth of lake-
induced stratocu and greatly limited any snow shower potential.
Can`t rule out a flurry or two through this morning over/near
the lake, but otherwise dry conditions are expected through at
least early this evening. Winds will ease and gradually easterly
with time this afternoon, but even with skies becoming mostly
sunny will continue to support quite a range in our high
temperatures today ranging from the mid-upper 30s near the lake
shore to the mid-40s well west and south of the lake across
interior northern IL/northwest IN.

Much farther to our northwest, GOES vapor imagery currently
shows a deep mid-level short wave transiting the Canadian
Rockies. As this feature propagates to the southeast across the
lower Canadian prairies and our Northern Plains tonight, large
scale height falls and resulting surface pressure falls will
induce a south-southwesterly low-level jet from the Plains into
the upper Midwest and western Lakes region tonight. Associated
warm advection and isentropic upglide is progged to develop a
narrow northwest to southeast oriented region of saturation
later this evening and overnight, deepest across northwest and
far northern IL. This narrow moist axis may produce a brief
period of light precipitation as it lifts northeast across
northern IL overnight. Model forecast thermodynamic profiles are
initially cold enough for this to be in the form of light snow,
though a warm nose develops around the 850 mb level in response
to WAA which would likely support a very brief period of
sleet/rain before precip ends. Thankfully, surface temperatures
will also be warming slowly toward the freezing mark especially
after midnight, which along with the expected brief duration of
precip looks to limit the duration of any light freezing rain in
any one place. Guidance is not to excited about QPF, and pops
top out around 30 percent with areas mainly north of I-88 most
likely to see this short period of light precip overnight.

The aforementioned surface low is progged to track south of
Lake Winnipeg and toward the north shore of Lake Superior
through Wednesday. Breezy southwest surface winds should develop
as the surface gradient tightens, and will likely gust to 30+
mph by afternoon. Much warmer air will accompany the breezy
conditions, with temperatures expected to surge into the mid-
upper 60s across much of the area. Guidance indicates some
degree of upper level cloud cover for much of the day, but if we
were to see more sunshine we could potentially see both
temperatures and winds overperform from current forecast and
have nudged both a little higher than the NBM blended guidance.
The surface low then passes north of Lake Superior Wednesday
night and Thursday, trailing a cold front slowly into the
forecast area. Shower chances ramp up within the narrow moist-
axis ahead of the front Wednesday night. While some embedded
thunder can`t be ruled out, current guidance depicts fairly
modest lapse rates/meager MUCAPE. The deep short wave passes
well north of the area Thursday morning, and while showers are
expected to continue along the front as it pushes slowly
southeast during the day, forcing diminishes. A perusal of
current global ensemble mean QPF for the 24 hours ending 00Z
Friday (7 pm Thursday) is less than a half inch during this
period.

The surface front, however, is progged to stall across or just
south of the forecast area late Thursday, while another mid-
level wave tracks across the upper Midwest Thursday night into
early Friday. With moisture already in place, and additional
moist advection wrapping north-northeastward from the western
Gulf, this wave appears poised to bring another round of
potentially heavier rain to the area - as indicated by an
ensemble mean QPF axis of around 0.75" (individual operational
runs indicate some 1.00"+ amounts, as well as greater MUCAPE
values) across parts of the cwa by late Friday. While the actual
frontal position is of somewhat low confidence in this time
period, its general presence and the anticipated increase in
cloud cover and rain also makes for lower temperature
confidence. There could potentially be some large temp ranges
Thursday and Friday, from the 50s/60s north of the front and
near Lake Michigan to the 70s south of the boundary.

Extended global/ensemble guidance is in decent agreement for
now with surface high pressure building across the Great Lakes
region Friday night into Saturday, potentially pushing the
frontal zone far enough south of the forecast area for a period
of dry weather. Beyond that, models are depicting amplification
of the upper pattern Sunday into Monday, as a long-wave upper
trough develops over the west coast. This, in turn, induces a
return of southwest low-level flow into the Midwest, with a
renewed push of warm/moist air into the region along with the
hint of several disturbances lifting into the the region from
the base of the western trough. While confidence is low in the
details at this distance, warmer and more active weather would
be supported into early next week.

Ratzer

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 630 AM CDT Tue Apr 7 2026

Key Aviation Messages for the current TAF period:

- Northeast winds becoming easterly, then eventually southeast
  after 06Z

- Less than a 30 percent chance for precipitation overnight
  into Wednesday morning

- Gusty southerly winds expected on Wednesday

VFR and northeast winds 10 to 15 knots prevail. Some FEW/SCT
decks just over 3000 ft AGL will continue through the morning,
but nothing lower. Winds will slowly turn to the east through
the day and diminish.

No changes in the precip forecast. Models continue to show a
weak wave passing over northern Illinois tonight which includes
a less than 30 percent chance for precipitation. The better
chances remain around the KRFD airspace, and cannot completely
rule it out over the Chicago terminals, but confidence remained
too low and was kept out of the TAF presently. Any precip that
does fall would do so for a limited time with little to no
accumulation. There is still some uncertainty with the precip
type. As temperatures warm through the night, any chances that
start out as snow can turn to rain, with a short window in
between for some wintry mix (sleet and/or freezing rain).

Winds will become southerly after 12Z tomorrow morning and
increase. Wind gusts 20 to 25 knots are expected with isolated
gusts to 30 knots.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 1 PM CDT this afternoon for the IL
     nearshore waters.

     Small Craft Advisory until 4 PM CDT this afternoon for the IN
     nearshore waters.

&&

$$

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